Cleaning equipment, cleaning method, semiconductor manufacturing device, and semiconductor device

ABSTRACT

A cleaning equipment and a cleaning method which prevent occurrence of an after-corrosion phenomenon, which would otherwise arise between Al and Cu; occurrence of defects in an area between Al and Cu, which would otherwise be caused when the time of operation for removing residual chlorine ions or the time of rinsing operation is increased; and occurrence of side etching; and enables attainment of a good etch profile. Ozone water (e.g., oxygen water of high concentration) supplied from an inlet port is introduced into a container from an outlet port by way of an inlet pipe. A robust surface oxide film can be formed on the surface of the wafer (i.e., a substrate to be rinsed). As a result, there can be prevented side etching of Al, which would otherwise be induced by the background art. Further, there can be prevented occurrence of defects in Al in the vicinity of a Cu deposit, which would otherwise be induced by a battery effect. Moreover, occurrence of an after-corrosion phenomenon can also be prevented.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention The present invention relates to cleaning equipment, a cleaning method, a semiconductor manufacturing device, and a semiconductor device. More particularly, the present invention relates to cleaning equipment and a cleaning method for removing a remover solvent adhering to a substrate to be rinsed, to a semiconductor manufacturing device for manufacturing a semiconductor device by use of the cleaning equipment, and to a semiconductor device manufactured by use of the cleaning equipment.

[0002] 2. Description of Related Art

[0003] In association with an increase in the scale of integration of semiconductor elements, rapid progress has recently been made toward attaining higher density by means of miniaturization of a pattern. Particularly in the fields of DRAM and application-specific integrated circuits (ASIC), there is required a miniaturized pattern having a size of one-half micron or less. Demand exists for a technique for removing dust particles or a cleaning technique applicable to such a miniaturized pattern. The cleaning technique using a remover solvent has widely been employed as one means of the dust particle removal technique or the cleaning technique.

[0004]FIGS. 9A through 9C show the most typical conventional cleaning equipment and method used for cleaning a substrate on which patterns such as semiconductor elements are formed. In connection with FIGS. 9A through 9C, reference numerals 31 a and 31 b designate remover solvents; 32 a, 32 b, 32 c designate wafer cassettes; 33 a, 33 b, 33 c designate substrates to be rinsed; 34 a and 34 b designate inlet ports for introducing the remover solvents 31 a and 31 b, respectively; 35 a, 35 b, and 35 c designate outlet ports for the remover solvents 31 a and 31 b; 36 a, 36 b, and 36 c designate containers; 38 a and 38 b designate remover solvent inlet ports of the inlet pipes 34 a and 34 b; 39 a and 39 b designate remover solvent outlet ports of the outlet valves 35 a and 35 b; 43 c designates a container rotary support shaft; and 44 c designates a container rotary support.

[0005]FIGS. 9A through 9C show processes for cleaning organic/inorganic polymer, dust particles, or residual chlorine ions adhering to the surface of a wafer, which wafer is the substrate 33, through use of a remover solution; for example, a hydrofluoric acid or sulfuric acid solution. As shown in FIG. 9A, the remover solution or solvent 31 a is introduced into the container 36 a by way of the remover solvent inlet port 34 a. The quantity of remover solvent 31 a to be introduced into the container 36 a is controlled by means of opening or closing the inlet valve 34 a or the outlet valve 39 a. A wafer, which is the substrate 33 a to be rinsed, is provided within the wafer cassette 32 a in the container 36 a and is left to sit in the remover solvent 31 a.

[0006]FIG. 9B shows a rinsing process for removing, for example, residual photoresist or chlorine ions adhering to the substrate or for replacing or rinsing a remover solvent remaining on the substrate. In connection with FIG. 9B, reference numeral 37 b designates purified wafer to be used for rinsing. As shown in FIG. 9B, the purified wafer 37 b is introduced into the container 36 b by way of the inlet port 34 b. The amount of purified wafer 37 b introduced into the container 36 b is controlled by means of opening or closing the inlet valve 34 b or the outlet valve 39 b. A wafer, which is the substrate 33 b, is provided within the wafer cassette 32 b in the container 36 a and is left to sit in the purified wafer 37 b.

[0007]FIG. 9C shows a process of removing moisture adhering to the wafer; i.e., the substrate 33 c, during the rinsing process. As shown in FIG. 9C, the wafer cassette 32 c is placed on the container rotary support 44 c within the container 36 c. The container rotary support shaft 43 c is rotated, thereby removing the moisture and water soluble powder remaining on the wafer; that is, the substrate 33 c, by way of the residual water solution outlet port 35 c.

[0008] The above-described background art increases the rinsing time for completely removing residual chlorine ions or photoresist from the substrate 33 b during the rinsing process shown in FIG. 9B or increases a period of time during which a rising operation is performed. For example, in the case of a wafer including an Al—Cu alloy interconnection substrate, electric charges stored in crystals located between heterogeneous metals; that is, an Al layer and a Cu layer, capture H₂O in association with an increase in rinsing time. As a result, an oxide film formed over the Al layer and the Cu layer is broken, thereby constituting the anode of a local battery. Reduction of dissolved oxygen arises on the entire surface of the cathode, whereby corrosion proceeds quickly, thus inducing an after-corrosion phenomenon. Alternatively, because of a battery effect in which migration of electric charge arises to thereby induce flow of an electric current, the Al layer is dissolved, thus causing defects in the Al layer and considerably deteriorating the geometry of the Al layer. Further, the battery effect considerably deteriorates the stable quality of a product.

[0009] If the rinsing time required in the rinsing process shown in FIG. 9B is shortened in order to prevent occurrence of the foregoing problems, chlorine ions or a remover solvent—which is in a pH range of comparatively-high acidic characteristic and is exemplified by a hydrofluoric acid or sulfuric acid solution—remains. The residual chlorine ions or remover solvent react with moisture in the atmosphere to form an AlOH-based reactive product, thereby chemically attacking an Al—Cu alloy interconnection pattern and causing a contact failure or a short circuit in the Al—Cu interconnection pattern. Thus, the reliability of a product is significantly deteriorated.

[0010] As described in Japanese Patent Publication Laid-Open No. 18992/1989, there is another cleaning method for introducing an ozone gas containing a high concentration of oxygen, in order to remove photoresist or reduce a pH value. Alternatively, as described in Japanese Patent Publication Laid-Open No. 11733/1987, there has also been conceived a cleaning method using an ozone gas containing a high concentration of oxygen. However, there has not been developed a cleaning method focusing on the importance of a cleaning operation; for example, a method comprising the steps of: mitigating the severity of an after-corrosion phenomenon arising in a position, for example, between an Al layer and a Cu layer, by means of migrating electric charge remaining in a metal interconnection pattern, such as an Al—Cu alloy interconnection; preventing occurrence of defects in the area between the Al layer and the Cu layer, which would otherwise be caused by an increase in the amount of residual chlorine ions or an increase in the rinsing time; and preventing side etching, thereby maintaining a good etch pattern.

[0011]FIG. 10 shows a cross-sectional view of the substrate 33C which has been cleaned by means of the conventional rinsing process shown in FIG. 9. As shown in FIG. 10, reference numeral 21 designates TiN which is an anti-reflection film; 22 designates an Al—Cu alloy interconnection pattern containing Al and 0.5% Cu; 23 designates a TiN/Ti alloy interconnection pattern; and 24 designates an oxide film layer or dielectric film layer formed for preventing occurrence of contact or short circuit with a lower interconnection, which would otherwise be caused at the time of formation of, for example, a multilayer interconnection. Reference numeral 25 designates a Cu deposit produced because of a difference in crystallization rate between Al and Cu or a difference in re-crystallization between Al and Cu during the cooling of a wafer, when an Al film layer is deposited by means of, for example, hot sputtering, in a preceding process during formation of an Al interconnection. Reference numeral 16 designates an example of defects which are formed in the Al—Cu alloy interconnection in the vicinity of the Cu deposit 25 as a result of the cleaning operation of background art. After an organic reactive product, an inorganic reactive product, residual chlorine, and photoresist have been removed from the side wall of an Al—Cu interconnection and from the surface of a wafer and after the resultant removed matter has been replaced or removed by means of H₂O of, for example, a remover solvent during a rinsing operation, the electric charge stored in the Al—Cu film at the time of formation of a fine interconnection during a pre-rinsing process breaks the surface oxide film formed on the side wall of the interconnection for anti-corrosion purpose. The anode of a local battery is formed between Cu deposited in the Al—Cu film and the adjacent Al—Cu layer formed around the thus-deposed Cu, and reduction of dissolved oxygen and generation of hydroxide ions OH⁻ arise on the entire surface of the cathode, inducing rapid progress of corrosion. Thus, the Al layer is dissolved, thereby forming the defects 16. Reference numeral 17 designates an example of after-corrosion phenomenon in which the defects 16 and the Al layer dissolved in the same process as formation of the defects 16 react with hydroxide ions OH⁻ to form an AlOH-based reactive product. Reference numeral 18 designates an example of dissolving of a metal layer and recession of the metal layer, which are induced by the side wall of the Al—Cu alloy interconnection reacting with hydroxide ions OH⁻ for reasons of disruption of the surface oxide film during replacement of the remover solvent with H₂O or during removal of the removal solvent.

[0012] If the time of the rinsing operation shown in FIG. 9B is shortened in order to solve the foregoing problem, there arises insufficient removal of, for example, a remover solvent, residual chlorine, an organic reactive product, an inorganic reactive product, and photoresist. In association with insufficient removal of these substances, residual chlorine or a remover solvent reacts with moisture in the atmosphere, thereby inducing an after-corrosion phenomenon. This phenomenon deteriorates the reliability of an interconnection, and the conventional cleaning method has encountered great difficulty in preventing occurrence of the after-corrosion phenomenon.

[0013] As mentioned above, the conventional cleaning equipment or method which removes a remover solvent adhering to the surface of a substrate after the substrate has been processed with a remover solution yields problems; that is, occurrence of an after-corrosion phenomenon at a position between Al and Cu, occurrence of side etching of the side wall of an Al interconnection, and occurrence of defects at a position between Al and Cu.

SUMMARY OF THE INVENTION

[0014] The present invention has been conceived to solve the foregoing problems and is aimed at providing cleaning equipment or a cleaning method capable of preventing occurrence of an after-corrosion phenomenon at a position between Al and Cu; preventing occurrence of defects at a position between Al and Cu, which would otherwise be caused by residual chlorine ions or an increase in a rinsing time; preventing occurrence of side etching; and maintaining a good etch profile.

[0015] According to a first aspect of the present invention, there is provide a cleaning equipment for removing remover solvent from a substrate to be rinsed, comprising: a container which retains the substrate therein and has an inlet port for introducing a solution into the container in a controllable manner, and an outlet port for discharging the solution outside in a controllable manner; and an oxygen-water-of-high-concentration inlet pipe for introducing oxygen water of high concentration into the container.

[0016] According to a second aspect of the present invention, there is provide a cleaning method for removing remover solvent from a substrate to be rinsed, comprising the step of: introducing oxygen water of high concentration into a container by way of an oxygen-water-of-high-concentration inlet pipe which introduces an oxygen-water-of-high-concentration, the container retaining the substrate therein and having an inlet port for introducing a solution into the container in a controllable manner and an outlet port for discharging the solution outside in a controllable manner.

[0017] According to a third aspect of the present invention, there is provide a semiconductor device manufacturing device for manufacturing a semiconductor device by utilization of the cleaning equipment according to the present invention.

[0018] According to a fourth aspect of the present invention, there is provide a semiconductor device cleaned by utilization of the cleaning equipment according to the present invention.

[0019] The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of the embodiments thereof taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIGS. 1A to 1C show the overall construction of cleaning equipment using oxygen water of high concentration for removing removal solvent from the surface of a substrate to be rinsed after the substrate has been processed through use of the remover solvent, according to a first embodiment of the present invention.

[0021]FIG. 2 is a cross-sectional view showing the substrate cleaned by means of a cleaning method under which ozone water is supplied as oxygen water of high concentration, according to the first embodiment.

[0022]FIG. 3 shows a comparison between the extent to which the side wall of an Al—Cu alloy interconnection was etched by means of a conventional cleaning method and the extent to which the side wall of an Al—Cu alloy interconnection was etched by means of a cleaning method according to a second embodiment.

[0023]FIG. 4 shows a comparison between the number of defects arising in Al in the vicinity of Cu deposits when the wafer is rinsed by means of a conventional cleaning method and the number of defects arising in Al in the vicinity of Cu deposits when the wafer is rinsed by means of a cleaning method according to a third embodiment.

[0024]FIG. 5 shows a comparison between the number of times an after-corrosion phenomenon arises when the wafer is rinsed by means of a conventional cleaning method and the number of times an after-corrosion phenomenon arises when the wafer is rinsed by means of a cleaning method according to a third embodiment.

[0025]FIG. 6 shows a comparison between the number of defects arising in Al in the vicinity of Cu deposits when the wafer is rinsed by means of a conventional cleaning method, the number of defects arising in Al in the vicinity of Cu deposits when the wafer is rinsed by means of a cleaning method using purified water and blowing of dry air, and the number of defects arising in Al in the vicinity of Cu deposits when the wafer is rinsed by means of a cleaning method according to a fourth embodiment.

[0026]FIG. 7 shows a cleaning method according to a fifth embodiment of the present invention, in which a substrate, which has been cleaned by use of remover solvent, is rinsed for removing the remover solvent from the surface of the substrate through use of purified wafer and hydrogen peroxide.

[0027]FIG. 8 shows a cleaning method according to a fifth embodiment of the present invention, in which a substrate, which has been cleaned by use of remover solvent, is rinsed for two minutes for removing the remover solvent from the surface of the substrate by means of supplying ozone water having a dissolved ozone level of 9 ppm.

[0028]FIGS. 9A through 9C show the most typical conventional cleaning equipment and method used for cleaning a substrate on which patterns such as semiconductor elements are formed.

[0029]FIG. 10 shows a cross-sectional view of the substrate 33C which has been cleaned by means of the conventional rinsing process shown in FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Preferred embodiments of the present invention will be described in detail hereinbelow by reference to the accompanying drawings.

[0031] First Embodiment

[0032]FIGS. 1A to 1C show the overall construction of cleaning equipment using oxygen water of high concentration for removing removal solvent from the surface of a substrate to be rinsed after the substrate has been processed through use of the remover solvent, according to a first embodiment of the present invention. As shown in FIGS. 1A through 1C, reference numeral 31 a and 31 b designate remover solvents, of which 31 b designates oxygen water of high concentration; 32 a, 32 b, and 32 c designate wafer cassettes; 33 a, 33 b, and 33 c designate substrates to be rinsed; 34 a and 34 b designate inlet ports for introducing the remover solvents 31 a and 31 b, respectively; 35 a, 35 b, and 35 c designate outlet ports for the remover solvents 31 a and 31 b; 36 a, 36 b, and 36 c designate containers; 38 a and 38 b designate remover solvent inlet ports of the respective remover solvent inlet ports 34 a and 34 b; 39 a and 39 b designate remover solvent outlet ports of the respective outlet valves 35 a and 35 b; 42 b designates an outlet port for the oxygen water of high concentration 31 b; 41 b designates an inlet pipe for the oxygen water of high concentration 31 b; 43 c designates a container rotary support shaft; and 44 c designates a container rotary support.

[0033]FIGS. 1A through 1C show processes for cleaning organic/inorganic polymer, dust particles, or residual chlorine ions adhering to the surface of a wafer, which wafer is the substrate 33 a, through use of a remover solution; for example, a hydrofluoric acid or sulfuric acid solution. As shown in FIG. 1A, the remover solution or solvent 31 a is introduced into the container 36 a by way of the remover solvent inlet port 34 a. The quantity of remover solvent 31 a to be introduced into the container 36 a is controlled by means of opening or closing the inlet valve 34 a or the outlet valve 39 a. A wafer, which is the substrate 33 a, is provided within the wafer cassette 32 a in the container 36 a and is left to sit in the remover solvent 31 a.

[0034]FIG. 1B shows a rinsing process for removing, for example, residual photoresist or chlorine ions adhering to the substrate or for replacing or rinsing a remover solvent remaining on the substrate. As shown in FIG. 1B, the ozone water 31 b which is, for example, oxygen water of high concentration and is supplied by way of the inlet port 41 b, is discharged into the container 36 b from the outlet port 42 b by way of the inlet pipe 43 b. As a result, a robust surface oxide film can be formed on the surface of the wafer, which is the substrate 33 b. The amount of ozone water 31 b introduced into the container 36 b is controlled by means of opening or closing the outlet valve 39 b. A wafer, which is the substrate 33 b, is provided within the wafer cassette 32 b in the container 36 a and is left to sit in the ozone water 31 b.

[0035]FIG. 1C shows a process of removing moisture adhering to the wafer; i.e., the substrate 33 c, during the rinsing process. As shown in FIG. 1C, the wafer cassette 32 c is placed on the container rotary support 44 c within the container 36 c. The container rotary support shaft 43 c is rotated, thereby removing the moisture and water soluble powder remaining on the wafer; that is, the substrate 33 c, by way of the residual water solution outlet port 35 c.

[0036] As a result of rinsing as mentioned above, there is prevented side etching of Al, which would otherwise arise under the background art. Consequently, there can be prevented occurrence of the defects 16 in Al in the vicinity of the Cu deposits 25, which would otherwise be caused by a battery effect. Thus, remover solvent is removed, and occurrence of an after-corrosion phenomenon can be prevented.

[0037]FIG. 2 is a cross-sectional view showing the substrate cleaned by means of a cleaning method under which ozone water is supplied as oxygen water of high concentration, according to the first embodiment. As shown in FIG. 2, reference numeral 21 designates TiN which acts as an anti-reflection film; 22 designates an Al—Cu alloy interconnection pattern containing Al and 0.5% Cu; 23 designates a TiN/Ti alloy interconnection pattern; and 24 designates an oxide film layer or dielectric film layer formed for preventing occurrence of contact or short circuit with a lower interconnection, which would otherwise be caused at the time of formation of, for example, a multilayer interconnection. Reference numeral 25 designates a Cu deposit produced because of a difference in crystallization rate between Al and Cu or a difference in re-crystallization between Al and Cu during the cooling of a wafer, when an Al film layer is deposited by means of, for example, hot sputtering, in a preceding process during formation of an Al interconnection. Reference numeral 211 designates a surface oxide film. When ozone water is supplied to the container, ozone dissolved in purified water are decomposed into oxygen within a short period of time. Hydroxy radicals (free radicals) and hydroperoxi radicals are produced as a result of direct reaction of ozone and decomposition of ozone. HO of the hydroxy radicals and HO₂ of the hydroperoxi radicals in combination form the surface oxide film 211.

[0038] Ozone is hydrolyzed by purified water, thereby producing hydroperoxi radicals, thereby inducing chain reaction and producing hydroperoxi radicals or hydroperoxi radicals having strong oxidation power. Recombination reaction of radicals results in formation of H₂O₂; i.e., hydrogen peroxide, thus terminating chained decomposition reaction. Formation of the robust oxide film 211 prevents side etching of the side wall of the Al interconnection and occurrence of defects in Al in the vicinity of the Cu deposits 25. Accordingly, occurrence of an after-corrosion phenomenon can be prevented, and a good etch profile is attained.

[0039] As mentioned above, in the first embodiment, the ozone water 31 b of high concentration supplied by way of the inlet port 41 b, for example, is discharged into the container 36 b from the outlet port 42 b by way of the inlet pipe 43 b. As a result, a robust surface oxide film can be formed on the surface of the wafer, which is the substrate 33 b. There can be prevented side etching of Al, which would otherwise be caused by the background art, and occurrence of the defects 16 in Al in the vicinity of the Cu deposits 25, which would otherwise be caused by the battery effect. Thus, removal of remover solvent and prevention of occurrence of an after-corrosion phenomenon can be implemented.

[0040] Second Embodiment

[0041]FIG. 3 shows a comparison between the extent to which the side wall of an Al—Cu alloy interconnection was etched by means of a conventional cleaning method and the extent to which the side wall of an Al—Cu alloy interconnection was etched by means of a cleaning method according to a second embodiment, in which remover solvent is removed from the surface of the substrate through use of ozone water or oxygen water of high concentration after the substrate has been processed with the remover solvent. In FIG. 3, the vertical axis represents the extent to which the side wall of Al—Cu alloy interconnection is etched (angstroms), and the horizontal axis represents a rinsing time during which rinsing with purified water and ozone water is performed (seconds). The comparison shown in FIG. 3 was performed on the basis of the assumption that a wafer—in which Al—Cu alloy interconnections are formed at a pitch of 0.40 μm so as to assume a line width of 0.40 μm by means of minute processing—as cleaned for residues or dust particles for 10 minutes through use of remover solvent containing dimethyl formaldehyde. By means of the conventional cleaning method, the wafer was rinsed for removing the remover solution through use of purified water, with the rising time being varied within a range of 30 sec. to 600 sec. Similarly, by means of the cleaning method according to the present invention, the wafer was rinsed while ozone water having a dissolved ozone level of 9 ppm was used as oxygen water of high concentration according to the present invention, with the rinsing time being varied within the range of 30 sec. to 600 sec. Subsequently, there was measured the extent to which the side wall of the Al—Cu alloy interconnection is etched, as indicated by the recession 18 which is shown in FIG. 10 and described in connection with the background art. In FIG. 3, line P1 shows the amount of side etching having arisen when the wafer was rinsed by means of the conventional rinsing method using purified water, and line P2 shows the amount of side etching having arisen when the wafer was rinsed by means of the rinsing method of the present invention using ozone water.

[0042] As shown in FIG. 3, during the rinsing operation P1 of the background art, the extent to which the sidewall of the Al—Cu alloy interconnection is etched is increased with an increase in rising time. In contrast, during the rinsing operation P2 according to the present invention using oxygen water of high concentration, no substantial change arises, through 600 sec., in the extent to which the side wall of the Al—Cu interconnection is etched. As compared with the minimum value of side etching which had occurred during the conventional rinsing operation P1 within a rising time of 30 sec. (side etching of Al assumes a value of about 100 angstroms), the minimum value of side etching which occurred during the rinsing operation P2 according to the rinsing method of the present invention using oxygen water of high concentration (side etching of Al assumes a value of about 20 angstroms) is diminished by about 80%. The result shows that, after having been processed with a remover solution, the substrate including an Al—Cu alloy interconnection is rinsed for removing the remover solvent from the surface of the substrate, through use of ozone water; that is, oxygen water of high concentration, by means of the rinsing equipment and method according to the present invention, thereby reducing the extent to which the side wall of the Al—Cu alloy interconnection is etched. In the present embodiment, the Al—Cu alloy interconnection has been used as a metal interconnection. Needless to say, the present embodiment yields the same advantage even when applied to a substrate having metal interconnections. Further, in the present embodiment, ozone water is employed as oxygen water of high concentration, the ozone water having a dissolved ozone level of 9 ppm. Further, it goes without saying that a similar tendency appears within at least the range where concentration of dissolved ozone is 1 ppm to 30 ppm. In the present embodiment, dimethyl formaldehyde has been used as a remover solution. Needless to say, the same tendency is attained, so long as the remover solution contains fluorine or ammonium of NH₄F (ammonium fluoride or sulfide).

[0043] As mentioned above, in the second embodiment, the wafer is rinsed for removing the remover solution through use of purified water, with the rising time being varied within the range of 30 sec. to 600 sec. Similarly, the wafer is rinsed while ozone water having a dissolved ozone level of 9 ppm is used as oxygen water of high concentration according to the present invention, with the rinsing time being varied within the range of 30 sec. to 600 sec. Subsequently, the extent to which the side wall of the Al—Cu alloy interconnection is etched, as indicated by the recession 18, is measured. As a result, as rinsing time is increased, through 600 sec., no substantial change arises in the extent to which the side wall of the Al—Cu interconnection is etched during the rinsing operation P2 using ozone water; that is, oxygen water of high concentration according to the present invention. Further, in connection with the minimum extent to which the side wall of the Al—Cu interconnection is etched, as compared with the extent to which Al of the Al—Cu interconnection was side-etched during the conventional rinsing operation p1 within a period of time 30 sec., the extent to which Al of the Al—Cu interconnection was side-etched during the rinsing operation using ozone water; that is, oxygen water of high concentration, is reduced by about 80%. Similar tendencies will appear within the range in which dissolved ozone content ranges from 1 ppm to 30 ppm.

[0044] Third Embodiment

[0045]FIG. 4 shows a comparison between the number of defects arising in Al in the vicinity of Cu deposits when the wafer is rinsed by means of a conventional cleaning method and the number of defects arising in Al in the vicinity of Cu deposits when the wafer is rinsed by means of a cleaning method according to a third embodiment, in which remover solvent is removed from the surface of the substrate through use of ozone water or oxygen water of high concentration after the substrate has been processed with the remover solvent. In FIG. 4, the vertical axis represents the number of defects arising in Al in the vicinity of Cu deposits, and the horizontal axis represents requirements for cleaning operation. The comparison shown in FIG. 4 is performed on the basis of the assumption that a wafer—in which Al—Cu alloy interconnections are formed at a pitch of 0.80 μm by means of minute processing so as to assume a line width of 0.80 μm—has been cleaned for removing residues or dust particles for 10 minutes through use of remover solvent containing dimethyl formaldehyde. By means of the conventional cleaning method, the wafer is rinsed for removing the remover solution through use of purified water, with the rinsing time being varied within a range of 30 sec. to 600 sec. Similarly, by means of the cleaning method according to the present invention, the wafer is rinsed while ozone water having a dissolved ozone level of 9 ppm is used as oxygen water of high concentration, with the rinsing time being varied within the range of 30 sec. to 600 sec. Subsequently, there is performed counting of the defects formed in the center of the respective wafer and counting of the defects formed in the outer periphery of the respective wafer, the defects being indicated by the recession 16 shown in FIG. 10 and described in connection with the background art. In FIG. 4, a shaded bar denotes the number of defects formed in Al in the center of the wafer, and an outline bar denotes the number of defects formed in Al in the outer periphery of the wafer.

[0046] The graphs provided on the left side of FIG. 4 show that 100 or more defects arise in the side wall of the Al—Cu alloy interconnection in the center and outer periphery of the wafer, which wafer is rinsed by means of the conventional cleaning method. In contrast, no substantial change arises in the number of defects in Al of the wafer which is rinsed by means of the cleaning method according to the present invention, even when the time of rinsing operation is increased from 30 sec. to 600 sec. The number of defects is 10 or less. Thus, in the substrate which is rinsed for removing remover solvent from the surface of the substrate after having been cleaned for removing residues or dust particles, through use of ozone water (oxygen water of high concentration) and by means of the cleaning equipment and method according to the present invention, formation of the robust oxide film 211 prevents occurrence of defects in Al of the Al—Cu alloy interconnection in the vicinity of the Cu deposits 25. In the present embodiment, an Al—Cu alloy interconnection is used as a metal interconnection. Needless to say, the present embodiment yields the same advantage even when applied to a substrate having metal interconnections. Further, in the present embodiment, ozone water is employed as oxygen water of high concentration, the ozone water having a dissolved ozone level of 9 ppm. Further, it goes without saying that a similar tendency appears within at least the range where concentration of dissolved ozone is 1 ppm to 30 ppm. In the present embodiment, dimethyl formaldehyde is used as a remover solution. Needless to say, the same tendency is attained, so long as the remover solution contains fluorine or ammonium of NH₄F (ammonium fluoride or sulfide) or contains sulfide.

[0047]FIG. 5 shows a comparison between the number of times an after-corrosion phenomenon arises when the wafer is rinsed by means of a conventional cleaning method and the number of times an after-corrosion phenomenon arises when the wafer is rinsed by means of a cleaning method according to a third embodiment, in which remover solvent is removed from the surface of the substrate through use of ozone water or oxygen water of high concentration after the substrate has been processed with the remover solvent. In FIG. 5, the vertical axis represents the number of times an after-corrosion phenomenon arises, and the horizontal axis represents a rinsing time during which rinsing with purified water and ozone water is performed (seconds). The comparison shown in FIG. 5 is performed on the basis of the assumption that a wafer—in which Al—Cu alloy interconnections are formed at a pitch of 0.40 μm by means of minute processing so as to assume a line width of 0.40 μm—has been cleaned for removing residues or dust particles for 10 minutes through use of remover solvent containing dimethyl formaldehyde. By means of the conventional cleaning method, the wafer is rinsed for removing the remover solution through use of purified water, with the rinsing time being varied within a range of 0 sec. to 120 sec. Similarly, by means of the cleaning method according to the present invention, the wafer is rinsed while ozone water having a dissolved ozone level of 9 ppm is used as oxygen water of high concentration according to the present invention, with the rinsing time being varied within the range of 0 sec. to 120 sec. The wafers are left in the atmosphere for 24 hours, and there is measured the number of times after-corrosion phenomenon arises, which phenomenon is indicated by reference numeral 17 shown in FIG. 10 and described in connection with the background art. In FIG. 5, line P3 shows the number of times an after-corrosion phenomenon arises when the substrate is rinsed by means of the conventional rinsing method using purified water, and line P4 shows the number of times an after-corrosion phenomenon arises when the substrate is rinsed by means of the rinsing method of the present invention using ozone water.

[0048] As shown in FIG. 5, in a case where a wafer (which has been cleaned for removing residues or dust particles) is not rinsed through use of purified water or ozone water, the chlorine ions or remover solvent residing in the substrate reacts with moisture in the atmosphere to induce an after-corrosion phenomenon. Occurrence of an after-corrosion phenomenon can be prevented by means of increasing the time of rinsing operation using purified water or ozone water. As can be seen from the rinsing operation using ozone water indicated by P4, occurrence of an after-corrosion phenomenon can be prevented within a rinsing time of 10 seconds, in association with formation of the robust oxide film 211. Thus, in a substrate which has, for example, an Al—Cu alloy interconnection and is rinsed for removing remover solvent from the surface of the substrate after having been cleaned for removing residues or dust particles, through use of ozone water (oxygen water of high concentration) and by means of the cleaning equipment and method according to the present invention, formation of the robust oxide film 211 prevents occurrence of an after-corrosion phenomenon, which would otherwise arise the Al—Cu alloy interconnection, within a short period of rinsing time. In the present embodiment, an Al—Cu alloy interconnection is used as a metal interconnection. Needless to say, the present embodiment yields the same advantage even when applied to a substrate having metal interconnections. Further, in the present embodiment, ozone water is employed as oxygen water of high concentration, the ozone water having a dissolved ozone level of 9 ppm. Further, it goes without saying that a similar tendency appears within at least the range where concentration of dissolved ozone is 1 ppm to 30 ppm. In the present embodiment, dimethyl formaldehyde is used as a remover solution. Needless to say, the same tendency is attained, so long as the remover solution contains fluorine or ammonium of NH₄F (ammonium fluoride or sulfide) or contains sulfide.

[0049] As mentioned above, in the third embodiment, the wafer is rinsed for removing the remover solution through use of purified water, with the rinsing time being varied within the range of 30 sec. to 600 sec. Similarly, the wafer is rinsed while ozone water having a dissolved ozone level of 9 ppm is used as oxygen water of high concentration according to the present invention, with the rinsing time being varied within the range of 30 sec. to 600 sec. Subsequently, there is performed measurement of the number of defects 16, such as those shown in FIG. 10, in the center and outer periphery of the wafer (i.e., the rinsed substrate). As a result, as rinsing time is increased, from 30 sec. to 600 sec., no substantial change arises in the number of defects formed in Al (10 or fewer defects). In a substrate which has, for example, Al—Cu alloy interconnections and has been cleaned, formation of the robust oxide film 211 prevents occurrence of defects in Al of the Al—Cu alloy interconnection in the vicinity of the Cu deposits 25. Similar tendencies will appear within at least the range in which dissolved ozone content is 1 ppm to 30 ppm.

[0050] Further, as removing processing of the remover solution, by means of the cleaning processing using a purified water and by means of the ozone water processing in which the ozone water has a dissolved ozone level of 9 ppm is used as oxygen water of high concentration according to the present invention, with the rinsing time being varied within a range of 0 sec. to 120 sec, the wafer is rinsed. The wafers are left in the atmosphere for 24 hours, and there is measured the number of times after-corrosion phenomenon arises, which phenomenon is indicated by reference numeral 17 shown in FIG. 10 and described in connection with the background art. The result of measurement shows that occurrence of an after-corrosion phenomenon can be prevented within a rinsing time of 10 seconds, in association with formation of the robust oxide film 211. Similar tendencies will appear within at least the range in which dissolved ozone content is 1 ppm to 30 ppm.

[0051] Fourth Embodiment

[0052]FIG. 6 shows a comparison between the number of defects arising in Al in the vicinity of Cu deposits when the wafer is rinsed by means of a conventional cleaning method, the number of defects arising in Al in the vicinity of Cu deposits when the wafer is rinsed by means of a cleaning method using purified water and blowing of dry air, and the number of defects arising in Al in the vicinity of Cu deposits when the wafer is rinsed by means of a cleaning method according to a fourth embodiment, in which remover solvent is removed from the surface of the substrate through use of ozone water or oxygen water of high concentration after the substrate has been processed with the remover solvent. In FIG. 6, the vertical axis represents the number of defects arising in Al in the vicinity of Cu deposits, and the horizontal axis represents requirements for cleaning operation. The comparison shown in FIG. 6 is performed on the basis of the assumption that a wafer—in which Al—Cu alloy interconnections are formed at a pitch of 0.50 μm by means of minute processing so as to assume a line width of 0.50 μm—has been cleaned for removing residues or dust particles for 10 minutes through use of remover solvent containing dimethyl formaldehyde. By means of the conventional cleaning method, the wafer is rinsed for removing the remover solution through use of purified water for ten minutes. Similarly, by means of the cleaning method according to the present invention, the wafer is rinsed for 10 minutes while ozone water having a dissolved ozone level of 9 ppm is used as oxygen water of high concentration. Subsequently, there is performed counting of the defects formed in the center of respective wafer and counting of the defects formed outer periphery of the wafer, the defects being indicated by the recession 16 shown in FIG. 10 and described in connection with the background art. In FIG. 6, a shaded bar denotes the number of defects formed in Al in the center of the wafer, and an outline bar denotes the number of defects formed in Al in the outer periphery of the wafer.

[0053] As shown in FIG. 6, when compared with the conventional cleaning method which uses purified water and is provided on the leftmost side of the drawing, a rinsing method—which is provided in the middle of the drawing and performs bubbling by means of supplying dry air—enables formation of a natural oxide film on the surface of a wafer (i.e., a substrate to be rinsed), and occurrence of defects in Al in the vicinity of the Cu deposits 25 is reduced slightly. However, a substantial improvement in prevention of occurrence of defects has not been attained. In the rinsing operation according to the present invention, which is shown in the rightmost end of the drawing and performs rinsing operation through use of ozone water (i.e., oxygen water of high concentration), hydroxy radicals (free radicals) and hydroperoxi radicals are produced as a result of direct reaction of ozone and decomposition of ozone. HO of the hydroxy radicals and HO₂ of the hydroperoxi radicals in combination form the robust surface oxide film 211, as mentioned in connection with the first embodiment, and the thus-formed oxide film 211 prevents occurrence of Al defects in the Cu deposits 25.

[0054] As has been described above, according to the fourth embodiment, the wafer is rinsed for removing the remover solution through use of purified water for ten minutes. Similarly, by means of the cleaning method according to the present invention, the wafer is rinsed for 10 minutes while ozone water having a dissolved ozone level of 9 ppm is used as oxygen water of high concentration. Subsequently, there are performed counting of the defects formed in the center of respective wafer and counting of the defects formed outer periphery of the wafer, the defects being indicated by the recession 16 shown in FIG. 10 and described in connection with the background art. The result of measurement shows that the robust oxide film 211 prevents occurrence of Al defects in the Cu deposits 25 during the rinsing operation using ozone water (oxygen water of high concentration), as mentioned in connection with the first embodiment.

[0055] Fifth Embodiment

[0056]FIG. 7 shows a cleaning method according to a fifth embodiment of the present invention, in which a substrate, which has been cleaned by use of remover solvent, is rinsed for removing the remover solvent from the surface of the substrate through use of purified wafer and hydrogen peroxide. More specifically, FIG. 7 is a cross-sectional view of the substrate having Al—Cu alloy interconnections stacked thereon and a tungsten plug serving as means for connecting the interconnections when the substrate is rinsed. In FIG. 7, those elements which are the same as those shown in FIG. 2 are assigned the same reference numerals, and repetition of their explanations is omitted here. As shown in FIG. 7, reference numeral 417 designates a tungsten plug for electrically interconnecting an upper layer section and a lower layer section of the substrate having the Al—Cu alloy interconnections stacked thereon; and 418 designates a void which has arisen during the course of a film growth operation and an embedding operation for forming the tungsten plug 417. The Al—Cu alloy interconnection 22 is in contact with the tungsten plug 417. However, under the rinsing method employing supply of hydrogen peroxide, a wafer is first subjected to a cleaning operation for removing residues or dust particles for ten minutes through use of a remover solvent containing dimethyl formaldehyde. Subsequently, when the wafer is rinsed for removing the remover solution through use of 1% aqueous hydrogen peroxide for two minutes, the tungsten plug 417 is dissolved by the amount indicated by A shown in FIG. 7. As a result, the oxide film formed on the surface of the tungsten plug 417 is broken and corroded, thereby causing a defect 416 in the Al—Cu alloy interconnection. No contact exists between the Al—Cu alloy interconnection 22 and the tungsten plug 417. The Cu deposit 25 causes a defect in the interconnection, and side etching of the interconnection also arises. In terms of a pH scale which expresses the acidity, alkalinity, or neutrality of a solution, Al enters a quasi-immobilized state within the range in which the pH of Al ranges from 4 to 8 or thereabouts. In water having pH 6 or greater, corrosion of Cu proceeds at very low speed under the protection of a corrosion product primarily consisting of Cu₂O, whence Cu enters a quasi-immobilized state. In a highly acidic range, Cu enters a quasi-immobilized state. However, the aqueous hydrogen peroxide—which has a concentration of 1% or thereabouts and is used in the embodiment—is acidic and may dissolve the Cu. Preferably, the concentration of aqueous hydrogen peroxide falls within the range of 1% to 5%.

[0057]FIG. 8 shows a cleaning method according to a fifth embodiment of the present invention, in which a substrate, which has been cleaned by use of remover solvent, is rinsed for two minutes for removing the remover solvent from the surface of the substrate by means of supplying ozone water having a dissolved ozone level of 9 ppm. More specifically, FIG. 8 is a cross-sectional view of the substrate having Al—Cu alloy interconnections stacked thereon and a tungsten plug serving as means for connecting the interconnections, as the substrate is rinsed. In FIG. 8, those elements which are the same as those shown in FIG. 7 are assigned the same reference numerals, and repetition of their explanations is omitted here. As shown in FIG. 8, ozone water forms a robust oxide layer 444, and the oxide layer 444 prevents side etching of the Al—Cu interconnection 22, which would otherwise be caused by dissolving of the tungsten plug 417 shown in FIG. 7. Further, the oxide layer 444 prevents occurrence of defects in Al in the vicinity of the Cu deposit 25. Consequently, occurrence of an after-corrosion phenomenon is also prevented, which in turn prevents dissolving of the tungsten plug 417. There is attained stable-yield production of a wafer having a multilayer interconnection. Further, attainment of a good etch profile becomes possible. In the present embodiment, an Al—Cu alloy interconnection is used as a metal interconnection. Needless to say, the present embodiment yields the same advantage even when applied to a substrate having metal interconnections. Further, in the present embodiment, ozone water is employed as oxygen water of high concentration, the ozone water having a dissolved ozone level of 9 ppm. Further, it goes without saying that a similar tendency appears within at least the range where concentration of dissolved ozone is 1 ppm to 30 ppm. In the present embodiment, dimethyl formaldehyde is used as a remover solution. Needless to say, the same tendency is attained, so long as the remover solution contains fluorine or ammonium of NH₄F (ammonium fluoride or sulfide) or contains sulfide.

[0058] As has been mentioned above, in the fifth embodiment, a substrate, which has been cleaned by use of remover solvent, is rinsed for two minutes for removing the remover solvent from the surface of the substrate by means of supplying ozone water having a dissolved ozone level of 9 ppm. Here, the substrate has Al—Cu alloy interconnections stacked thereon and a tungsten plug serving as means for connecting the interconnections. Ozone water enables formation of the robust oxide layer 444, and the oxide layer 444 prevents side etching of the Al—Cu interconnection 22, which would otherwise be caused by dissolving of the tungsten plug 417. Further, the oxide layer 444 prevents occurrence of defects in Al in the vicinity of the Cu deposit 25. Consequently, occurrence of an after-corrosion phenomenon is also prevented, which in turn prevents dissolving of the tungsten plug 417. There is attained stable-yield production of a wafer having a multilayer interconnection. Further, attainment of a good etch profile becomes possible.

[0059] By means of utilization of the cleaning equipment set forth, there can be embodied a semiconductor device manufacturing device for manufacturing a semiconductor device having the foregoing characteristics, such as good etch profile. Further, there can be embodied a semiconductor device characterized by the good etch profile produced by utilization of the foregoing cleaning equipment.

[0060] As has been described above, the cleaning equipment and method according to the present invention enable formation of a robust surface oxide film on the surface of a wafer (substrate to be rinsed), by means of introduction of ozone water (oxygen water of high concentration) into a container from an outlet port by way of an inlet pipe. As a result, the present invention can provide cleaning equipment and a cleaning method which prevent occurrence of an after-corrosion phenomenon, which would otherwise arise between Al and Cu; occurrence of defects in an area between Al and Cu, which would otherwise be caused when the time of operation for removing residual chlorine ions or the time of rinsing operation is increased; and occurrence of side etching; and enables attainment of a good etch profile.

[0061] In the cleaning equipment, a solution introduced into said container by way of the inlet port may be purified water.

[0062] In the cleaning equipment, the oxygen water of high concentration may be ozone water.

[0063] In the cleaning equipment, a dissolved ozone content may range from 1 ppm to 30 ppm.

[0064] In the cleaning equipment, the oxygen water of high concentration may be aqueous hydrogen peroxide.

[0065] In the cleaning equipment, the concentration of the aqueous hydrogen peroxide may range from 1 to 5%.

[0066] In the cleaning method, a solution introduced into the container by way of the inlet port may be purified water.

[0067] In the cleaning method, the oxygen water of high concentration may be ozone water.

[0068] In the cleaning method, a dissolved ozone content may range from 1 ppm to 30 ppm.

[0069] In the cleaning method, the oxygen water of high concentration may be aqueous hydrogen peroxide.

[0070] In the cleaning method, the concentration of the aqueous hydrogen peroxide may range from 1 to 5%.

[0071] The present invention has been described in detail with respect to various embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and it is the invention, therefore, in the appended claims to cover all such changes and modifications as fall within the true spirit of the invention.

[0072] The entire disclosure of Japanese Patent Application No. 2000-294636 filed on Sep. 27, 2000 including specification, claims, drawings and summary are incorporated herein by reference in its entirety. 

What is claimed is:
 1. Cleaning equipment for removing remover solvent from a substrate to be rinsed, comprising: a container which retains the substrate therein and has an inlet port for introducing a solution into the container in a controllable manner, and an outlet port for discharging the solution outside in a controllable manner; and an oxygen-water-of-high-concentration inlet pipe for introducing oxygen water of high concentration into the container.
 2. The cleaning equipment according to claim 1, wherein a solution introduced into said container by way of the inlet port is purified water.
 3. The cleaning equipment according to claim 2, wherein the oxygen water of high concentration is ozone water.
 4. The cleaning equipment according to claim 3, wherein a dissolved ozone content ranges from 1 ppm to 30 ppm.
 5. The cleaning equipment according to claim 2, wherein the oxygen water of high concentration is aqueous hydrogen peroxide.
 6. The cleaning equipment according to claim 5, wherein the concentration of the aqueous hydrogen peroxide ranges from 1 to 5%.
 7. A cleaning method for removing remover solvent from a substrate to be rinsed, comprising the step of: introducing oxygen water of high concentration into a container by way of an oxygen-water-of-high-concentration inlet pipe which introduces an oxygen-water-of-high-concentration, the container retaining the substrate therein and having an inlet port for introducing a solution into the container in a controllable manner and an outlet port for discharging the solution outside in a controllable manner.
 8. The cleaning method according to claim 7, wherein a solution introduced into the container by way of the inlet port is purified water.
 9. The cleaning method according to claim 8, wherein the oxygen water of high concentration is ozone water.
 10. The cleaning method according to claim 9, wherein a dissolved ozone content ranges from 1 ppm to 30 ppm.
 11. The cleaning method according to claim 10, wherein the oxygen water of high concentration is aqueous hydrogen peroxide.
 12. The cleaning method according to claim 11, wherein the concentration of the aqueous hydrogen peroxide ranges from 1 to 5%.
 13. A semiconductor device manufacturing device for manufacturing a semiconductor device by utilization of the cleaning equipment according to any one of claims 1 through
 6. 